The term “content” is used in the broadcast and communications industries to denote digital files, such as, for example, video files (e.g., movies), audio files (e.g., music), image files, and text files. Content is distributed by a content provider to end users over wired and wireless networks to devices that have content renderers that render the content, e.g., display the content on a display device and/or playback the content on an audio playback device. For example, a cable television provider or multiple service operator (MSO) may allow a paying customer to download a movie that the user then watches on a laptop computer, a television set, a mobile telephone, etc.
Content providers manage the distribution of content (e.g., downloading, streaming, etc.) by using one or more of a variety of digital rights management (DRM) techniques. DRM techniques are used to prevent unauthorized users from gaining access to content while allowing authorized users to access the content. This is typically accomplished by encrypting the content when it is distributed to the authorized user, and providing the user with a key that allows the user's device to decrypt the content so that it can be rendered. DRM, however, encompasses more than securing content from unauthorized access. It also encompasses describing, identifying, trading, monitoring, and tracking of all forms of rights usages over both tangible and intangible assets. The term “tangible assets” refers to physical content, whereas the term “intangible assets” generally refers to copyrights in the content held by copyrights holders.
Recently, consumer demand has been increasing for ways to allow end users of content to use, or share, the content in multiple devices, e.g., the television, a personal computer (PC), a laptop computer, a mobile telephone, etc. Content providers are interested in providing end users with this capability, but need to be able to ensure that the provided content is fully secured and that control over access and usage rights are controlled. Various DRM techniques have been proposed to address these goals.
One known DRM technique that is directed toward achieving these goals is implemented in iTunes products offered by Apple Computers, Inc. The DRM technique implemented in these products allows a user to share the same downloaded content among a fixed number of devices. The devices that share the content are managed by a master device, such as a PC, that checks the devices in and out to ensure that no more than an allowed number of devices are sharing the content at a given time. This DRM technique, however, is implemented in software, which is prone to subversion. In fact, this particular DRM technique has already been compromised by someone who was able to convert protected content into unprotected content.
DRM techniques have also been implemented in hardware. DRM hardware solutions generally are more secure or less easily compromised than DRM software solutions. Nevertheless, to date, no suitable hardware implementations have been developed that achieve the goals of allowing users to simultaneously share the same content among multiple devices while ensuring that the content remains secure, i.e., cannot be accessed by unauthorized or unintended users.
Accordingly, a need exists for a secure way of allowing content to be shared among multiple devices.